How do I assign properties of a child object based on a property from the parent using AutoFixture?

Question

I have an Order object that has a Shipments collection. Shipment has a property called OrderId. How can I customize AutoFixture to generate an order where order.Shipments.All(s => s.OrderId == order.Id) is true?

I've tried the following techniques already with no success:

fixture.Customize<Order>(c => c.Do(o => {
    // This is called before the Order's properties have been populated,
    // so there are no shipments yet.
    foreach (var s in o.Shipments) {
        s.OrderId = o.Id;
    }
}));

---

fixture.Customize<Order>(c => c.Do(o => {
    o.Id = c.Create<Guid>();       // System.InvalidCastException
    o.Shipments = new List<Shipment>(c.CreateMany<Shipment>());
    foreach (var shipment in o.Shipments) {
        shipment.OrderId = o.Id;
    }
}));

---

class OrderGenerator : ISpecimenBuilder {
    public object Create(object request, ISpecimenContext context) {
        if (request as Type == typeof(Order)) {
            // ObjectCreationException due to circular reference
            var order = (Order)context.Resolve(request);
            foreach (var shipment in order.Shipments) {
                shipment.OrderId = order.Id;
            }
        }
    }
}
fixture.Customizations.Add(new OrderGenerator());

What is the best way to do this?